Method for iterative first arrival picking using global path tracing

Abstract

Systems and methods for automated first arrival picking are disclosed. The method includes obtaining a seismic dataset composed of a plurality of seismic gathers and determining a pilot for each gather, where the pilot includes a position on an ordinate axis for each seismic trace representing a first arrival. The method continues iteratively until a stopping criterion is met by creating a preconditioned gather using the pilot, determining a differential pilot using global path tracing subject to a constraint and incrementing the pilot using the differential pilot to create a total picked first arrival. Once the stopping criterion has been met, the method further includes determining a final picked first arrival based on the total picked first arrival, determining a seismic velocity model from the final picked first arrival using a tomographic inversion and creating a seismic image using the seismic velocity model and the seismic dataset.

What is claimed is: 
     
       1. A method, comprising:
 obtaining a seismic dataset for a subterranean region of interest, wherein the seismic dataset comprises a plurality of seismic gathers and each seismic gather comprises a plurality of spatially-ordered seismic traces; 
 determining a pilot for each seismic gather, wherein the pilot comprises a position on an ordinate axis for each seismic trace within the seismic gather; 
 for each seismic gather, iteratively or recursively, until a stopping criterion is met:
 creating a preconditioned gather using the pilot, wherein the preconditioned gather comprises a plurality of preconditioned traces, 
 determining a differential pilot, using global path tracing subject to a constraint, wherein the differential pilot comprises an increment on the ordinate axis for each preconditioned gather, and 
 incrementing the pilot using the differential pilot to create a total picked first arrival; 
 
 determining a final picked first arrival based on the total picked first arrival; 
 determining a seismic velocity model from the final picked first arrival using a tomographic inversion; and 
 creating a seismic image for the subterranean region of interest using the seismic velocity model and the seismic dataset. 
 
     
     
       2. The method of  claim 1 , further comprising identifying, using a seismic interpretation workstation, a drilling target within the subterranean region of interest based, at least in part, on the seismic image. 
     
     
       3. The method of  claim 2 , further comprising planning a wellbore path using a wellbore path planning system to intersect the drilling target. 
     
     
       4. The method of  claim 3 , further comprising drilling a wellbore guided by the wellbore path using a drilling system. 
     
     
       5. The method of  claim 1 , wherein the stopping criterion comprises a predetermined total picked first arrival quality metric. 
     
     
       6. The method of  claim 1 , wherein creating the preconditioned gather comprises determining the plurality of preconditioned traces, wherein each preconditioned trace is generated by shifting one of the plurality of spatially-ordered seismic traces along the ordinate axis by a shift determined from the pilot. 
     
     
       7. The method of  claim 1 , wherein determining the differential pilot, using the global path tracing subject to the constraint comprises:
 calculating an accumulated amplitude along a plurality of global paths across the preconditioned gather, wherein each global path comprises one sample drawn from each preconditioned trace subject to the constraint; 
 determining a path of maximum accumulated amplitude based on identifying the global path with a greatest accumulated amplitude; and 
 determining the differential pilot from a separation of the pilot and the path of maximum accumulated amplitude. 
 
     
     
       8. The method of  claim 7 , wherein the constraint specifies a maximum separation on the ordinate axis between candidate path samples on spatially-adjacent traces. 
     
     
       9. A non-transitory computer readable memory comprising computer-executable instructions stored thereon that, when executed on a processor, cause the processor to perform:
 receiving a seismic dataset for a subterranean region of interest, wherein the seismic dataset comprises a plurality of seismic gathers and each seismic gather comprises a plurality of spatially-ordered seismic traces; 
 determining a pilot for each seismic gather, wherein the pilot comprises a position on an ordinate axis for each seismic trace within the seismic gather; 
 for each seismic gather, iteratively or recursively, until a stopping criterion is met:
 creating a preconditioned gather using the pilot, wherein the preconditioned gather comprises a plurality of preconditioned traces, 
 determining a differential pilot, using global path tracing subject to a constraint, wherein the differential pilot comprises an increment on the ordinate axis for each preconditioned gather, and 
 incrementing the pilot using the differential pilot to create a total picked first arrival; 
 
 determining a final picked first arrival based on the total picked first arrival; 
 determining a seismic velocity model from the final picked first arrival using a tomographic inversion; and 
 creating a seismic image for the subterranean region of interest using the seismic velocity model and the seismic dataset. 
 
     
     
       10. The non-transitory computer readable memory of  claim 9 , wherein the ordinate axis indicates time. 
     
     
       11. The non-transitory computer readable memory of  claim 9 , wherein creating the preconditioned gather comprises determining the plurality of preconditioned traces, wherein each preconditioned trace is generated by shifting one of the plurality of spatially-ordered seismic traces along the ordinate axis by a shift determined from the pilot. 
     
     
       12. The non-transitory computer readable memory of  claim 9 , wherein determining the differential pilot, using the global path tracing subject to the constraint comprises:
 calculating an accumulated amplitude along a plurality of global paths across the preconditioned gather, wherein each global path comprises one sample drawn from each preconditioned trace subject to the constraint; 
 determining a path of maximum accumulated amplitude based on identifying the global path with a greatest accumulated amplitude; and 
 determining the differential pilot from a separation of the pilot and the path of maximum accumulated amplitude. 
 
     
     
       13. The non-transitory computer readable memory of  claim 12 , wherein the constraint specifies a maximum separation on the ordinate axis between candidate path samples on spatially-adjacent traces. 
     
     
       14. A system, comprising:
 a seismic survey system configured to acquire a seismic dataset for a subterranean region of interest, wherein the seismic dataset comprises a plurality of seismic gathers and each seismic gather comprises a plurality of spatially-ordered seismic traces; and 
 a seismic processor configured to: 
 receive the seismic dataset for the subterranean region of interest from the seismic survey system, 
 determine a pilot for each seismic gather, wherein the pilot comprises a position on an ordinate axis for each seismic trace within the seismic gather,
 for each seismic gather, iteratively or recursively, until a stopping criterion is met: 
 create a preconditioned gather using the pilot, wherein the preconditioned gather comprises a plurality of preconditioned traces, 
 determine a differential pilot, using global path tracing subject to a constraint, wherein the differential pilot comprises an increment on the ordinate axis for each preconditioned gather, 
 increment the pilot using the differential pilot to create a total picked first arrival, 
 
 determine a final picked first arrival based on the total picked first arrival; 
 determine a seismic velocity model from the final picked first arrival using a tomographic inversion, and 
 create a seismic image for the subterranean region of interest using the seismic velocity model and the seismic dataset; and 
 a seismic interpretation workstation configured to identify a drilling target within the subterranean region of interest based, at least in part, on the seismic image. 
 
     
     
       15. The system of  claim 14 , further comprising a wellbore path planning system configured to plan a wellbore path to intersect the drilling target. 
     
     
       16. The system of  claim 15 , further comprising a drilling system to drill a wellbore guided by the wellbore path. 
     
     
       17. The system of  claim 14 , wherein the stopping criterion comprises a predetermined total picked first arrival quality metric. 
     
     
       18. The system of  claim 14 , wherein creating the preconditioned gather comprises determining the plurality of preconditioned traces, wherein each preconditioned trace is generated by shifting one of the plurality of spatially-ordered seismic traces along the ordinate axis by a shift determined from the pilot. 
     
     
       19. The system of  claim 14 , wherein determining the differential pilot using the global path tracing subject to the constraint comprises:
 calculating an accumulated amplitude along a plurality of global paths across the preconditioned gather, wherein each global path comprises one sample drawn from each preconditioned trace subject to the constraint; 
 determining a path of maximum accumulated amplitude based on identifying the global path with a greatest accumulated amplitude; and 
 determining the differential pilot from a separation of the pilot and the path of maximum accumulated amplitude. 
 
     
     
       20. The system of  claim 19 , wherein the constraint specifies a maximum separation on the ordinate axis between candidate path samples on spatially-adjacent traces.